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TOMOYO Linux Cross Reference
Linux/arch/cris/arch-v32/kernel/signal.c

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  1 /*
  2  * Copyright (C) 2003, Axis Communications AB.
  3  */
  4 
  5 #include <linux/sched.h>
  6 #include <linux/mm.h>
  7 #include <linux/kernel.h>
  8 #include <linux/signal.h>
  9 #include <linux/errno.h>
 10 #include <linux/wait.h>
 11 #include <linux/ptrace.h>
 12 #include <linux/unistd.h>
 13 #include <linux/stddef.h>
 14 #include <linux/syscalls.h>
 15 #include <linux/vmalloc.h>
 16 
 17 #include <asm/io.h>
 18 #include <asm/processor.h>
 19 #include <asm/ucontext.h>
 20 #include <asm/uaccess.h>
 21 #include <arch/ptrace.h>
 22 #include <arch/hwregs/cpu_vect.h>
 23 
 24 extern unsigned long cris_signal_return_page;
 25 
 26 /* Flag to check if a signal is blockable. */
 27 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 28 
 29 /*
 30  * A syscall in CRIS is really a "break 13" instruction, which is 2
 31  * bytes. The registers is manipulated so upon return the instruction
 32  * will be executed again.
 33  *
 34  * This relies on that PC points to the instruction after the break call.
 35  */
 36 #define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;
 37 
 38 /* Signal frames. */
 39 struct signal_frame {
 40         struct sigcontext sc;
 41         unsigned long extramask[_NSIG_WORDS - 1];
 42         unsigned char retcode[8];       /* Trampoline code. */
 43 };
 44 
 45 struct rt_signal_frame {
 46         struct siginfo *pinfo;
 47         void *puc;
 48         struct siginfo info;
 49         struct ucontext uc;
 50         unsigned char retcode[8];       /* Trampoline code. */
 51 };
 52 
 53 void do_signal(int restart, struct pt_regs *regs);
 54 void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
 55                       struct pt_regs *regs);
 56 /*
 57  * Swap in the new signal mask, and wait for a signal. Define some
 58  * dummy arguments to be able to reach the regs argument.
 59  */
 60 int
 61 sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
 62                long srp, struct pt_regs *regs)
 63 {
 64         mask &= _BLOCKABLE;
 65         spin_lock_irq(&current->sighand->siglock);
 66         current->saved_sigmask = current->blocked;
 67         siginitset(&current->blocked, mask);
 68         recalc_sigpending();
 69         spin_unlock_irq(&current->sighand->siglock);
 70         current->state = TASK_INTERRUPTIBLE;
 71         schedule();
 72         set_thread_flag(TIF_RESTORE_SIGMASK);
 73         return -ERESTARTNOHAND;
 74 }
 75 
 76 int
 77 sys_sigaction(int signal, const struct old_sigaction *act,
 78               struct old_sigaction *oact)
 79 {
 80         int retval;
 81         struct k_sigaction newk;
 82         struct k_sigaction oldk;
 83 
 84         if (act) {
 85                 old_sigset_t mask;
 86 
 87                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 88                     __get_user(newk.sa.sa_handler, &act->sa_handler) ||
 89                     __get_user(newk.sa.sa_restorer, &act->sa_restorer))
 90                         return -EFAULT;
 91 
 92                 __get_user(newk.sa.sa_flags, &act->sa_flags);
 93                 __get_user(mask, &act->sa_mask);
 94                 siginitset(&newk.sa.sa_mask, mask);
 95         }
 96 
 97         retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL);
 98 
 99         if (!retval && oact) {
100                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
101                     __put_user(oldk.sa.sa_handler, &oact->sa_handler) ||
102                     __put_user(oldk.sa.sa_restorer, &oact->sa_restorer))
103                         return -EFAULT;
104 
105                 __put_user(oldk.sa.sa_flags, &oact->sa_flags);
106                 __put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask);
107         }
108 
109         return retval;
110 }
111 
112 int
113 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
114 {
115         return do_sigaltstack(uss, uoss, rdusp());
116 }
117 
118 static int
119 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
120 {
121         unsigned int err = 0;
122         unsigned long old_usp;
123 
124         /* Always make any pending restarted system calls return -EINTR */
125         current_thread_info()->restart_block.fn = do_no_restart_syscall;
126 
127         /*
128          * Restore the registers from &sc->regs. sc is already checked
129          * for VERIFY_READ since the signal_frame was previously
130          * checked in sys_sigreturn().
131          */
132         if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
133                 goto badframe;
134 
135         /* Make that the user-mode flag is set. */
136         regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));
137 
138         /* Restore the old USP. */
139         err |= __get_user(old_usp, &sc->usp);
140         wrusp(old_usp);
141 
142         return err;
143 
144 badframe:
145         return 1;
146 }
147 
148 /* Define some dummy arguments to be able to reach the regs argument. */
149 asmlinkage int
150 sys_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
151               struct pt_regs *regs)
152 {
153         sigset_t set;
154         struct signal_frame __user *frame;
155         unsigned long oldspc = regs->spc;
156         unsigned long oldccs = regs->ccs;
157 
158         frame = (struct signal_frame *) rdusp();
159 
160         /*
161          * Since the signal is stacked on a dword boundary, the frame
162          * should be dword aligned here as well. It it's not, then the
163          * user is trying some funny business.
164          */
165         if (((long)frame) & 3)
166                 goto badframe;
167 
168         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
169                 goto badframe;
170 
171         if (__get_user(set.sig[0], &frame->sc.oldmask) ||
172             (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1],
173                                                  frame->extramask,
174                                                  sizeof(frame->extramask))))
175                 goto badframe;
176 
177         sigdelsetmask(&set, ~_BLOCKABLE);
178         spin_lock_irq(&current->sighand->siglock);
179 
180         current->blocked = set;
181 
182         recalc_sigpending();
183         spin_unlock_irq(&current->sighand->siglock);
184 
185         if (restore_sigcontext(regs, &frame->sc))
186                 goto badframe;
187 
188         keep_debug_flags(oldccs, oldspc, regs);
189 
190         return regs->r10;
191 
192 badframe:
193         force_sig(SIGSEGV, current);
194         return 0;
195 }
196 
197 /* Define some dummy variables to be able to reach the regs argument. */
198 asmlinkage int
199 sys_rt_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
200                  struct pt_regs *regs)
201 {
202         sigset_t set;
203         struct rt_signal_frame __user *frame;
204         unsigned long oldspc = regs->spc;
205         unsigned long oldccs = regs->ccs;
206 
207         frame = (struct rt_signal_frame *) rdusp();
208 
209         /*
210          * Since the signal is stacked on a dword boundary, the frame
211          * should be dword aligned here as well. It it's not, then the
212          * user is trying some funny business.
213          */
214         if (((long)frame) & 3)
215                 goto badframe;
216 
217         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
218                 goto badframe;
219 
220         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
221                 goto badframe;
222 
223         sigdelsetmask(&set, ~_BLOCKABLE);
224         spin_lock_irq(&current->sighand->siglock);
225 
226         current->blocked = set;
227 
228         recalc_sigpending();
229         spin_unlock_irq(&current->sighand->siglock);
230 
231         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
232                 goto badframe;
233 
234         if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT)
235                 goto badframe;
236 
237         keep_debug_flags(oldccs, oldspc, regs);
238 
239         return regs->r10;
240 
241 badframe:
242         force_sig(SIGSEGV, current);
243         return 0;
244 }
245 
246 /* Setup a signal frame. */
247 static int
248 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
249                  unsigned long mask)
250 {
251         int err;
252         unsigned long usp;
253 
254         err = 0;
255         usp = rdusp();
256 
257         /*
258          * Copy the registers. They are located first in sc, so it's
259          * possible to use sc directly.
260          */
261         err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
262 
263         err |= __put_user(mask, &sc->oldmask);
264         err |= __put_user(usp, &sc->usp);
265 
266         return err;
267 }
268 
269 /* Figure out where to put the new signal frame - usually on the stack. */
270 static inline void __user *
271 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
272 {
273         unsigned long sp;
274 
275         sp = rdusp();
276 
277         /* This is the X/Open sanctioned signal stack switching. */
278         if (ka->sa.sa_flags & SA_ONSTACK) {
279                 if (!on_sig_stack(sp))
280                         sp = current->sas_ss_sp + current->sas_ss_size;
281         }
282 
283         /* Make sure the frame is dword-aligned. */
284         sp &= ~3;
285 
286         return (void __user *)(sp - frame_size);
287 }
288 
289 /* Grab and setup a signal frame.
290  *
291  * Basically a lot of state-info is stacked, and arranged for the
292  * user-mode program to return to the kernel using either a trampiline
293  * which performs the syscall sigreturn(), or a provided user-mode
294  * trampoline.
295   */
296 static int
297 setup_frame(int sig, struct k_sigaction *ka,  sigset_t *set,
298             struct pt_regs * regs)
299 {
300         int err;
301         unsigned long return_ip;
302         struct signal_frame __user *frame;
303 
304         err = 0;
305         frame = get_sigframe(ka, regs, sizeof(*frame));
306 
307         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
308                 goto give_sigsegv;
309 
310         err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
311 
312         if (err)
313                 goto give_sigsegv;
314 
315         if (_NSIG_WORDS > 1) {
316                 err |= __copy_to_user(frame->extramask, &set->sig[1],
317                                       sizeof(frame->extramask));
318         }
319 
320         if (err)
321                 goto give_sigsegv;
322 
323         /*
324          * Set up to return from user-space. If provided, use a stub
325          * already located in user-space.
326          */
327         if (ka->sa.sa_flags & SA_RESTORER) {
328                 return_ip = (unsigned long)ka->sa.sa_restorer;
329         } else {
330                 /* Trampoline - the desired return ip is in the signal return page. */
331                 return_ip = cris_signal_return_page;
332 
333                 /*
334                  * This is movu.w __NR_sigreturn, r9; break 13;
335                  *
336                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
337                  * reasons and because gdb uses it as a signature to notice
338                  * signal handler stack frames.
339                  */
340                 err |= __put_user(0x9c5f,         (short __user*)(frame->retcode+0));
341                 err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
342                 err |= __put_user(0xe93d,         (short __user*)(frame->retcode+4));
343         }
344 
345         if (err)
346                 goto give_sigsegv;
347 
348         /*
349          * Set up registers for signal handler.
350          *
351          * Where the code enters now.
352          * Where the code enter later.
353          * First argument, signo.
354          */
355         regs->erp = (unsigned long) ka->sa.sa_handler;
356         regs->srp = return_ip;
357         regs->r10 = sig;
358 
359         /* Actually move the USP to reflect the stacked frame. */
360         wrusp((unsigned long)frame);
361 
362         return 0;
363 
364 give_sigsegv:
365         if (sig == SIGSEGV)
366                 ka->sa.sa_handler = SIG_DFL;
367 
368         force_sig(SIGSEGV, current);
369         return -EFAULT;
370 }
371 
372 static int
373 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
374                sigset_t *set, struct pt_regs * regs)
375 {
376         int err;
377         unsigned long return_ip;
378         struct rt_signal_frame __user *frame;
379 
380         err = 0;
381         frame = get_sigframe(ka, regs, sizeof(*frame));
382 
383         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
384                 goto give_sigsegv;
385 
386         /* TODO: what is the current->exec_domain stuff and invmap ? */
387 
388         err |= __put_user(&frame->info, &frame->pinfo);
389         err |= __put_user(&frame->uc, &frame->puc);
390         err |= copy_siginfo_to_user(&frame->info, info);
391 
392         if (err)
393                 goto give_sigsegv;
394 
395         /* Clear all the bits of the ucontext we don't use.  */
396         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
397         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
398         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
399 
400         if (err)
401                 goto give_sigsegv;
402 
403         /*
404          * Set up to return from user-space. If provided, use a stub
405          * already located in user-space.
406          */
407         if (ka->sa.sa_flags & SA_RESTORER) {
408                 return_ip = (unsigned long) ka->sa.sa_restorer;
409         } else {
410                 /* Trampoline - the desired return ip is in the signal return page. */
411                 return_ip = cris_signal_return_page + 6;
412 
413                 /*
414                  * This is movu.w __NR_rt_sigreturn, r9; break 13;
415                  *
416                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
417                  * reasons and because gdb uses it as a signature to notice
418                  * signal handler stack frames.
419                  */
420                 err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
421 
422                 err |= __put_user(__NR_rt_sigreturn,
423                                   (short __user*)(frame->retcode+2));
424 
425                 err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
426         }
427 
428         if (err)
429                 goto give_sigsegv;
430 
431         /*
432          * Set up registers for signal handler.
433          *
434          * Where the code enters now.
435          * Where the code enters later.
436          * First argument is signo.
437          * Second argument is (siginfo_t *).
438          * Third argument is unused.
439          */
440         regs->erp = (unsigned long) ka->sa.sa_handler;
441         regs->srp = return_ip;
442         regs->r10 = sig;
443         regs->r11 = (unsigned long) &frame->info;
444         regs->r12 = 0;
445 
446         /* Actually move the usp to reflect the stacked frame. */
447         wrusp((unsigned long)frame);
448 
449         return 0;
450 
451 give_sigsegv:
452         if (sig == SIGSEGV)
453                 ka->sa.sa_handler = SIG_DFL;
454 
455         force_sig(SIGSEGV, current);
456         return -EFAULT;
457 }
458 
459 /* Invoke a signal handler to, well, handle the signal. */
460 static inline int
461 handle_signal(int canrestart, unsigned long sig,
462               siginfo_t *info, struct k_sigaction *ka,
463               sigset_t *oldset, struct pt_regs * regs)
464 {
465         int ret;
466 
467         /* Check if this got called from a system call. */
468         if (canrestart) {
469                 /* If so, check system call restarting. */
470                 switch (regs->r10) {
471                         case -ERESTART_RESTARTBLOCK:
472                         case -ERESTARTNOHAND:
473                                 /*
474                                  * This means that the syscall should
475                                  * only be restarted if there was no
476                                  * handler for the signal, and since
477                                  * this point isn't reached unless
478                                  * there is a handler, there's no need
479                                  * to restart.
480                                  */
481                                 regs->r10 = -EINTR;
482                                 break;
483 
484                         case -ERESTARTSYS:
485                                 /*
486                                  * This means restart the syscall if
487                                  * there is no handler, or the handler
488                                  * was registered with SA_RESTART.
489                                  */
490                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
491                                         regs->r10 = -EINTR;
492                                         break;
493                                 }
494 
495                                 /* Fall through. */
496 
497                         case -ERESTARTNOINTR:
498                                 /*
499                                  * This means that the syscall should
500                                  * be called again after the signal
501                                  * handler returns.
502                                  */
503                                 RESTART_CRIS_SYS(regs);
504                                 break;
505                 }
506         }
507 
508         /* Set up the stack frame. */
509         if (ka->sa.sa_flags & SA_SIGINFO)
510                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
511         else
512                 ret = setup_frame(sig, ka, oldset, regs);
513 
514         if (ka->sa.sa_flags & SA_ONESHOT)
515                 ka->sa.sa_handler = SIG_DFL;
516 
517         if (ret == 0) {
518                 spin_lock_irq(&current->sighand->siglock);
519                 sigorsets(&current->blocked, &current->blocked,
520                         &ka->sa.sa_mask);
521                 if (!(ka->sa.sa_flags & SA_NODEFER))
522                         sigaddset(&current->blocked, sig);
523                 recalc_sigpending();
524                 spin_unlock_irq(&current->sighand->siglock);
525         }
526 
527         return ret;
528 }
529 
530 /*
531  * Note that 'init' is a special process: it doesn't get signals it doesn't
532  * want to handle. Thus you cannot kill init even with a SIGKILL even by
533  * mistake.
534  *
535  * Also note that the regs structure given here as an argument, is the latest
536  * pushed pt_regs. It may or may not be the same as the first pushed registers
537  * when the initial usermode->kernelmode transition took place. Therefore
538  * we can use user_mode(regs) to see if we came directly from kernel or user
539  * mode below.
540  */
541 void
542 do_signal(int canrestart, struct pt_regs *regs)
543 {
544         int signr;
545         siginfo_t info;
546         struct k_sigaction ka;
547         sigset_t *oldset;
548 
549         /*
550          * The common case should go fast, which is why this point is
551          * reached from kernel-mode. If that's the case, just return
552          * without doing anything.
553          */
554         if (!user_mode(regs))
555                 return;
556 
557         if (test_thread_flag(TIF_RESTORE_SIGMASK))
558                 oldset = &current->saved_sigmask;
559         else
560                 oldset = &current->blocked;
561 
562         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
563 
564         if (signr > 0) {
565                 /* Whee!  Actually deliver the signal.  */
566                 if (handle_signal(canrestart, signr, &info, &ka,
567                                 oldset, regs)) {
568                         /* a signal was successfully delivered; the saved
569                          * sigmask will have been stored in the signal frame,
570                          * and will be restored by sigreturn, so we can simply
571                          * clear the TIF_RESTORE_SIGMASK flag */
572                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
573                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
574                 }
575 
576                 return;
577         }
578 
579         /* Got here from a system call? */
580         if (canrestart) {
581                 /* Restart the system call - no handlers present. */
582                 if (regs->r10 == -ERESTARTNOHAND ||
583                     regs->r10 == -ERESTARTSYS ||
584                     regs->r10 == -ERESTARTNOINTR) {
585                         RESTART_CRIS_SYS(regs);
586                 }
587 
588                 if (regs->r10 == -ERESTART_RESTARTBLOCK){
589                         regs->r10 = __NR_restart_syscall;
590                         regs->erp -= 2;
591                 }
592         }
593 
594         /* if there's no signal to deliver, we just put the saved sigmask
595          * back */
596         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
597                 clear_thread_flag(TIF_RESTORE_SIGMASK);
598                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
599         }
600 }
601 
602 asmlinkage void
603 ugdb_trap_user(struct thread_info *ti, int sig)
604 {
605         if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
606                 /* Zero single-step PC if the reason we stopped wasn't a single
607                    step exception. This is to avoid relying on it when it isn't
608                    reliable. */
609                 user_regs(ti)->spc = 0;
610         }
611         /* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
612            not withing any configured h/w breakpoint range). Synchronize with
613            what already exists for kernel debugging.  */
614         if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
615                 /* Break 8: subtract 2 from ERP unless in a delay slot. */
616                 if (!(user_regs(ti)->erp & 0x1))
617                         user_regs(ti)->erp -= 2;
618         }
619         sys_kill(ti->task->pid, sig);
620 }
621 
622 void
623 keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
624                  struct pt_regs *regs)
625 {
626         if (oldccs & (1 << Q_CCS_BITNR)) {
627                 /* Pending single step due to single-stepping the break 13
628                    in the signal trampoline: keep the Q flag. */
629                 regs->ccs |= (1 << Q_CCS_BITNR);
630                 /* S flag should be set - complain if it's not. */
631                 if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
632                         printk("Q flag but no S flag?");
633                 }
634                 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
635                 /* Assume the SPC is valid and interesting. */
636                 regs->spc = oldspc;
637 
638         } else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
639                 /* If a h/w bp was set in the signal handler we need
640                    to keep the S flag. */
641                 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
642                 /* Don't keep the old SPC though; if we got here due to
643                    a single-step, the Q flag should have been set. */
644         } else if (regs->spc) {
645                 /* If we were single-stepping *before* the signal was taken,
646                    we don't want to restore that state now, because GDB will
647                    have forgotten all about it. */
648                 regs->spc = 0;
649                 regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT));
650         }
651 }
652 
653 /* Set up the trampolines on the signal return page. */
654 int __init
655 cris_init_signal(void)
656 {
657         u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL);
658 
659         /* This is movu.w __NR_sigreturn, r9; break 13; */
660         data[0] = 0x9c5f;
661         data[1] = __NR_sigreturn;
662         data[2] = 0xe93d;
663         /* This is movu.w __NR_rt_sigreturn, r9; break 13; */
664         data[3] = 0x9c5f;
665         data[4] = __NR_rt_sigreturn;
666         data[5] = 0xe93d;
667 
668         /* Map to userspace with appropriate permissions (no write access...) */
669         cris_signal_return_page = (unsigned long)
670           __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE);
671 
672         return 0;
673 }
674 
675 __initcall(cris_init_signal);
676 

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